This research involves the development of fully-automated instrumentation procedures to evaluate microregional circulation in tissues. Phase I results have demonstrated that cell-permeant fluorescent dyes or "molecular microspheres" can be spatially located in sequential fluorescence images recorded from frozen tissue blocks during organ serial sectioning. Statistical limitations imposed on current fluorescent and radioactive microsphere methods are removed by the use of molecule-sized microspheres, expanding greatly the details of organ-flow mapping. During Phase I, several dyes have been identified as having excellent retention in heart vascular systems and their regional deposition correlates strongly with simultaneously injected 15-micron diameter fluorescent microspheres. Both the validity of the molecular microsphere approach and the feasibility of the imaging methodology have been demonstrated. Phase II will concentrate on adapting and optimizing the imaging system for microregional flow imaging and will involve a rigorous validation of the technique through collaboration with the Fluorescent Microsphere Resource Center at the University of Washington. This project will provide researchers with instrumentation for rapid, automatic evaluation of microregional flow in tissue volumes less than 1/1000 the size of those possible with current techniques, while using procedures similar to the standard procedures involved in radioactive and fluorescent microsphere flow determinations. PROPOSED COMMERCIAL APPLICATIONS: Instrumentation and methods to rapidly and automatically evaluate molecular microsphere distributions in tissue will find applications in laboratories engaged in physiology and circulation research. The development of molecular microsphere methodology in the proposal will significantly enhance the commercial market for the Barlow Scientific microsphere imaging system in such laboratories.